diff --git a/include/xo/indentlog/log_level.hpp b/include/xo/indentlog/log_level.hpp
index 8b470891..a4392286 100644
--- a/include/xo/indentlog/log_level.hpp
+++ b/include/xo/indentlog/log_level.hpp
@@ -1,5 +1,7 @@
 /* @file log_level.hpp */
 
+#pragma once
+
 #include <cstdint>
 
 namespace xo {